On November 10, 1993, a Cessna 421 (registration N1600B) was involved in an aviation accident near Miami, FL. Investigators recorded the probable cause as: FAILURE OF THE PILOT-IN-COMMAND TO OBTAIN THE PROPER ASSISTANCE AFTER BEING NOTIFIED OF A FUEL LEAK FROM THE LEFT WING FUEL TANKS AFTER REFUELING. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A fuel leak near the left main landing gear was identified during preflight checks. The pilot attributed the spill to overfilling the tanks. Shortly after, an engine backfire triggered an explosion and fire in the engine nacelle.
What happened
During the preflight preparation, the aircraft's fuel tanks were filled by ground crew. A lineworker on the ramp noticed fuel pooling on the ground adjacent to the left main landing gear assembly. The individual immediately informed the pilot of the visible spillage.
The pilot acknowledged the observation and explained that the leakage was a result of overfilling the fuel tanks during the refueling process. Rather than halting operations or addressing the spill further, the airplane was moved to its operational position. During the startup sequence for the left engine, the engine backfired. This event was immediately followed by an explosion and subsequent fire near the left engine nacelle area.
The investigation
The available source material does not provide details on mechanical examinations or post-incident inspections of the aircraft components.